Data communications switches are generally adapted to receive packets on network ports, inspect the incoming packets for virtual local area network (VLAN) tags, classify the packets in accordance with forwarding policies, and forward the packets in specified VLAN or an alternate VLAN depending on the policies. Modernly, ports are configured to respond in accordance with one of a plurality of modes including a fixed port mode, protocol-enforced port mode, or tagged port mode. If the port is configured as a fixed port, tagged and untagged packets are routed to a default VLAN associated with the port. If the port is configured as a protocol-enforced port, the incoming packets are routed to a VLAN associated with the inbound protocol whether the packets are tagged or untagged. If the port is in a tagged port mode, tagged packets entering the switch are routed to a tagged VLAN and untagged packets are routed to a default VLAN. Unfortunately, a port configured in accordance with these modes may not be able to simultaneously accommodate packets from a conventional host and tagged packets from a voice-over-Internet-Protocol (VoIP) device. If a personal computer (PC) and VoIP phone were connected to a mobility port, for example, the untagged traffic from the PC and tagged traffic from the phone are forwarded on the protocol-dependent VLAN regardless of the VLAN tag specified by phone.
In addition to the above, IEEE Std. 802.1Q and IEEE Draft Std. 802.1V define standard VLAN classification protocols. Std. 802.1Q provides two basic VLAN classification rules: (1) if an inbound packet contains a tag header having a valid VLAN identifier, assign the packet to a VLAN associated with the VLAN identifier; and (2) if an inbound packet does not contain a tag header having a valid VLAN identifier, assign the packet to a VLAN-associated with the ingress port. Like Std. 802.1Q, Std. 802.1V assigns an inbound packet having a VLAN tag to the identified VLAN if the VLAN identifier is valid. Unlike Std. 802.1Q, however, Std. 802.1V specifies that an inbound packet be assigned to a VLAN associated with the ingress port and protocol type of the inbound packet if the inbound packet does not contain a tag header having a valid VLAN identifier. Stds. 802.1Q and 802.1V also provide VLAN tagging rules for adding a tag header including an assigned VLAN identifier to a packet prior to transmitting the packet on an egress port.
Although the Standards attempt to reconcile the tagged and protocol-enforced port modes, the prior art does not address integration of the various modes to produce a “hybrid port” having modes that are standards-compliant as well as modes that are not standards-compliant. There is, therefore, a need for a hybrid port adapted to assign an inbound packet containing a tag header having a valid VLAN identifier the packet to a VLAN associated with the VLAN identifier in the packet, to a VLAN associated with the ingress port, or to a VLAN associated with a protocol type of the packet.